1. Field of the Invention
This invention relates to computer memory arrangements and, more particularly, to methods and apparatus for slowing the read operation of selected memory cells in order to obtain accurate data.
2. History of the Prior Art
Modern computer systems make extensive use of long term memory. Typically this memory is provided by one or more hard (fixed) disks. A hard disk is an electro-mechanical device which includes one or more flat circular magnetically-coated disks fixed to rotate rapidly about a central axis. A mechanical arm driven by electrical signals places a magnetic head over each side of each disk to write to positions on the disk or to read from those positions. These positions lie in sectors, a number of which form one complete track on one side of a disk. Each sector is capable of storing a fixed number of bytes of data (typically 512 bytes). Depending on formatting, a single side of a disk may have over six hundred tracks. A typical disk drive used in personal computers today is capable of storing forty megabytes or more of data.
Such hard disk drives are very useful and have become almost a necessity to the operation of personal computers. However, such electro-mechanical drives do have their drawbacks. They are relatively heavy and increase the weight of a computer, especially a portable computer, significantly. They also are relatively bulky and require a significant amount of space within a computer. Their use requires a significant amount of the power and in a portable computer leads to significant battery power consumption. More importantly, electro-mechanical hard disk drives are very susceptible to shock. A hard drive within a portable computer which is dropped is quite likely to cease functioning. This can cause a catastrophic loss of data.